if you just count the result, the only solution is

if you just count the result, the only solution is

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送交者: xj 于 2008-04-30, 10:48:54:

回答: 昨天那个3个BOOLEANS组合的问题我用集合论解决了由 Enlighten 于 2008-04-30, 10:30:51:

\sum_{m=0}^N{C(N,m)}

i.e., sum of N choose m, where m=0,...,N

that is the same as 2^N (无内容) - Enlighten (0 bytes) 2008-04-30, 10:52:25 (222504)